The problem of burglaries in the home has steadily increased over the last several years. The "modus operandi" of the typical suburb burglar has been found to fall into a definite pattern. This pattern is to canvass a neighborhood looking for houses where the occupants are away, usually on an extended vacation. When this has been determined, the burglars make the hit in the night with the entry usually being gained by breaking the pane of a sash window, reaching in and releasing the usual rotary lock, raising the window and climbing in through the window. Once inside, the house is ransacked for valuables and the burglar makes his exit, usually within 6-7 minutes, through the door or back through the open window.
There have been several suggested systems for providing supplemental locks to the windows for use primarily when the occupants of the building are away to deter these burglaries. One accepted method that is recommended by many police departments and other law enforcement agencies is very simple. It comprises drilling a hole through the abutting frame members of the sash windows and inserting a nail through the hole to hold the windows from sliding up or down.
This supplemental locking device has worked in some cases in the past, and is simple and inexpensive. But, it suffers the drawback that it is now easily detected by the burglar and once detected the nail or pin is easily removed manually. Then, access can still be obtained and the burglar completes his job within his allowed safe time.
There have been several suggestions for improved lock assemblies to overcome the shortcoming of the basic pin-type lock being too easy to defeat by the burglar. One of these prior art developments is described in the U.S. Pat. No. to Gough et al 3,288,510, issued Nov. 29, 1966. This patent involves utilizing a machine screw in place of the pin and an insert for the screw to engage in one of the sash members. This device, while also serving a purpose of providing an additional lock, is more expensive since the insert is required and the screw can normally be removed since the burglar usually has the most common tools, such as a screw driver, in his possession during his attempt at entry. By the simple act of removal of the screw, the burglar still meets his safe time requirement.